Accelerator Potentiometer Circuits

F-code Section C-code

PS S5.8 5460 12 Volt Transistor Controller

Version no T-code 000 RMX

15,000 times per second by the control circuitry, while the ratio of the on and off times is regulated by the input of the accelerator potentiometer. This is called Pulse Width Modulation. When the transistors are on, current flows through the drive motor and builds up energy in the motor's magnetic field. When the transistors turn off, this stored energy continues to flow in the drive motor through the freewheel, or flyback diode. Thus, the average motor current is greater then the average battery current and smooth, step less control of the power delivered to the drive motor is achieved with very little power loss in the control components.

2.7. Accelerator Potentiometer Circuits

The accelerator potentiometer is used to signal the Curtis ® PMC controller of the desired motor speed. By controlling the position of the accelerator potentiometer the operator can control the travel speed of the truck. The accelerator potentiometer is connected between terminals 2 and 3 on the Curtis ® PMC controller. When in neutral the resistance through the accelerator potentiometer is high, approximately 5500 +/- 100 ohms. As the truck controls are operated to a higher travel speed the resistance through the accelerator potentiometer decreases. The resistance should decrease to below 50 ohms at full speed. The resistance of the accelerator potentiometer is used to regulate the voltage potential on terminals 2 and 3 of the Curtis® PMC controller. In neutral with a high resistance through the accelerator potentiometer the voltage potential, with respect to battery negative will be 1.85 volts +/- 10 percent on terminal 3 and 5.20 volts +/- 10 percent on terminal 2. When the controls are operated to high speed and the resistance through the accelerator potentiometer is at a minimum the voltage potential, with respect to battery negative, will equalize at 4.3 volts +/- 10 percent on both terminals 2 and 3. Because the accelerator potentiometer is not polarity oriented it does not matter which lead of the potentiometer is connected to either terminal 2 or 3. The accelerator potentiometer is used to control the speed of the truck during normal operation. When the red emergency